Lexmark C750 Service Manual - Page 130

5060-00x Step 3 Actions and questions Press the TMC pin in the magenta cartridge contact assembly to make sure it actuates the TMC switch on the developer HVPS. When the TMC pin is pressed you hear a click when the switch actuates. Check for mechanical interference between the contact block and the developer HVPS. Note: You may need to turn the printer off to hear the click. Does the magenta TMC switch on the developer HVPS board actuate properly when the TMC pin is pressed? Yes Replace the cartridge. No Go to step 4 4 Check the developer HVPS board to make sure it is not cracked or broken. Is the developer HVPS board cracked or broken?' Replace the developer HVPS board assembly. Go to step 6 Go to step 5 5 Check the mounting of the developer HVPS. Make sure the screws that mount the power supply are properly tightened and the board is positioned and mounted correctly. Is the developer HVPS mounted correctly? If the board is incorrectly installed, install it correctly. Make sure all the mounting screws are tightened. Recheck the printer to see if a 941 error is still displayed. Correctly connect the cable. 6 Make sure the developer HVPS cable is correctly installed on the developer board assembly. Is the cable correctly installed? Go to step 7 7 Make sure the developer HVPS cable is correctly installed at J20 on the engine board. Is the cable properly installed? Go to step 8 Correctly connect the cable. 8 Check the voltage at connector J20-5 on the engine board while pressing the magenta TMC pin in the cartridge contact assembly. Does the voltage change when the pin is pressed? Replace the engine board assembly. Go to step 9 9 Check the voltage at connector J20-5 when the magenta TMC switch is pressed. Does the voltage measure approximately +3.3 V dc? Go to step 10 Go to step 11 10 Check the developer HVPS to engine board cable for damage, broken connections, or wire and shorts between adjacent pins. Are there any signs of damage to the cable? Replace the cable. Replace the developer HVPS board assembly. 11 Disconnect the developer HVPS cable from connector J20 on the engine board. Measure the voltage on connector J20-5 on the engine board. Does the voltage measure approximately 0 V dc? Replace the engine board assembly. Replace the developer HVPS and developer HVPS to engine board cable. 2-96 Service Manual